1. Field of the Invention
The invention relates to building construction materials, a method for making construction elements of a building, and an expansion joint to allow for thermal expansion or contraction of a building constructed from such construction elements. More particularly, the invention provides an underlying expanded polyurethane foam supported from appropriately flanged metal I-beam studs, the underlying foam supporting a hard, smooth, durable layer of sprayed-on mixture of fiberglass and cementitious composition which sets to form a fire-resistant, waterproof and durable external surface, firmly secured to the foam with the aid of an appropriate bonding agent. The panels are useful as structural walls or in forming a roof.
2. Description of the Prior Art
Preformed wall panels for use in building construction are known in the prior art. For example, Lemelson in U.S. Pat. No. 3,298,883, issued Jan. 17, 1967, discloses a wall, ceiling, or a partition made from a curved wall panel comprising a flexible array of self-supporting strips shaped to deform and jointed together to form a honeycomb structure. A cellular plastic polymeric material, such as expanded polyurethane, can comprise the frame supporting cellular sheet or slab on which a mortar or filler material can be sprayed to form a hard shell when it hardens. However, the simplicity, conformity with traditional standards of construction, and cost effectiveness of a straight wall or roof panel made from appropriately flanged metal I-beam studs are not present in the Lemelson patent teachings.
Also known in the prior art is a method of constructing a roof having a thermal insulating layer in pre-cut blocks, blanks or sheets, preferably a closed cellular material. The exterior surface is formed of material such as concrete block covered with a roof wearing surfacing composition. Such a roof construction requires rather cumbersome assembly procedures, including extensive cutting, shaping, and fitting operations to conform the individual component parts with the overall roof size requirements. Moreover, such a roof construction appears to have utility only for roofs of flat configuration, which are capable of withstanding foot traffic, rather than roof constructions of the conventional peaked or sloping configuration. Other patents showing an insulated roof construction include U.S. Pat. No. 3,094,447, issued June 18, 1963 to Chamberlain, and U.S. Pat. No. 3,698,972, issued Oct. 17, 1972 to Lenzner.
The prior art further discloses use of insulating joints for joining heat insulating elements and for providing a strong rigid structure therebetween, such as in U.S. Pat. No. 3,251,912, patented May 17, 1966 by Fish. A channel filled with foamed insulating material is bonded to adjacent insulating elements by an adhesive to form a firm joint. Such a joint, however, does not appear to allow for thermal expansion or contraction of the external surface.
U.S. Pat. No. Re. 28,976, reissued Sept. 28, 1978 to Zinn, discloses a method for forming and assembling a sound attenuating wall between fixed structure channels.
It is also known to prepare a cementitious composition of matter for spray forming a concrete layer which hardens to a firm shell, used as a substitute for plaster, gunite, or the like, in building construction. Such a material is manufactured by Owens-Corning and marketed under the trade name "BlocBond", which material is a mixture of Portland cement, hydrated lime, calcium chloride, calcium stearate, and alkali-resistant fiberglass filaments having a length of about one-half inch. Such a composition, however, does not ordinarily effectively bond to polyurethane foam, such as can be applied by spraying and curing to form a stable, insulating, construction material substrate, as those skilled in the art are aware.